Production of anthraquinonyl nitriles



United States Patent 2,852,534 PRODUCTION or ANTHRAQUINONYL NITRILESErwin Klingsberg, Mountainside, N. 1., assignor to American CyanamidCompany, New York, N. Y., a corporation of Maine No Drawing. ApplicationNovember 18, 1957 Serial No. 696,905

Claims. Cl. 260-369 This invention relates to a new process for thepreparation of 2-anthraquinony1 ni'triles, and more specifically itrelates to a process of preparing Z-anthraquinonyl nitriles by thereaction of Z-anthraquinonyl aldazines with chlorine at elevatedtemperatures in dichlorobenzene solution.

Anthroquinonyl nitriles have up to now been prepared by the Sandmeyerreaction, which requires the diazotization of the corresponding amineand the reaction of the diazo with cuprous cyanide. This process isoften very clumsy and difiicult to work with because of the use of thecyanide which causes hazards. It furthermore gives low yields in manycases. There is a great need for a ready preparation of anthraquinonenitriles since such compounds can be polymerized to form triazines, orcan be hydrolyzed to form free anthraquinone carboxylic acids. Forexample, for anthraquinone-Z-carboxylic acids, the known preparationusually involves the oxidation of a side chain alkyl, a reaction whichis characterized by heavy foaming which is diflicult to control. A goodpreparation of anthraquinone acids from the more readily obtainablealdehydes is much needed in the art.

I have found that when a 2-anthraquinonyl aldazine is chlorinated withfree chlorine in o-dichlorobenzene solution at elevated temperatures,preferably above 60 C., and preferably at much higher temperatures thesole product isolated is the corresponding Z-cyanoanthraquinone.

In the past, aldazines have been chlorinated to give chloroaldazines,and these chlorinated aldazines can, upon vigorous treatment, give cyanocompounds. This has never been done in the anthraquinone series. It ismost surprising to find that in a specific solvent and under specificconditions, the intermediate chloroaldazine is not isolated and cannotbe detected, but rather the reaction proceeds readily to thecorresponding Z-cyanoanthraquinone. This is all the more surprisingsince different conditions give the chloroaldazine.

The chlorinating agent and the solvent are very critical. Thetemperature in the process of my invention must be kept above 60 C.Preferably much higher temperatures of the order of l20-165 C., areused. The product readily separates upon cooling the dichlorobenzenesolution, and can be isolated by filtration and washing.

The anthraquinone rings cannot have amino or hydroxy substituents duringthe chlorinations, since these groups cause ring chlorination instead ofattack on the aldazine side chain. However, nitro groups can be presentwhich can be transformed later to amino, alkoxy, hydroxy, etc. Thus theprocess of this invention is applicable to the azines ofanthraquinone-2-aldehyde, lchloroanthraquinone-Z-aldehyde,l-nitroanthraquinone- 2-aldehyde, 3-chloroanthraquinone-2-aldehyde,4-chloroanthraquinone-2-aldehyde, 5 nitroanthraquinone-Z-aldehyde,5,6,7,8-tetrachloroanthraquinone-Z-aldehyde, and the like.

My invention can be illustrated by the following ex- 2,852,534 PatentedSept. 16, 1958 ICC amples in which parts are by weight unless otherwisespecified.

Example 1 A mixture of 0.2 part of Z-anthraquinone carboxaldazine and 3parts by volume of ortho-dichlorobenzene is heated at 160-165 C., whilebeing treated with a stream of chlorine until the reaction is complete.On cooling the product separates and is washed with benzene; M. P.216217 C.

Example 2 01 A steady stream of chlorlne is passed through a mix-Example 3 O NO:

The procedure of Example 2 is followed using an equivalent amount ofl-nitro anthraquinonyl-Z-carboxaldazine in place of the1-chloroanthraquinone-2-carboxaldazine.

S-nitro anthraquinone-Z-carboxaldazine when used in place of the l-nitroisomer, yields the corresponding 5-nitro-2-cyano anthraquinone.

Example 4 C 0 OH Thirteen and four tenths parts of the product of Ex- 34 mediateafor a'numberofvatdyes. This amino acid is 2. The process ofclaim 1 in which the temperature also preparable by the similarhydrolysis of the product is 120-165 C. of Example 3 followed byreduction. 3. The process of claim 2.in which the anthraquinonyl Iclaim: adlazine is Z-anthraquirionecarboxaldazine. "1- A pr f pr p ringan unaminated, y y 5 4. The process of claim 2 in which theanthraquinonyl ated z-cyanoanthfaquinone Which Comprises heating aaldazine is 1-chloro-anthraquinone-2-carboxaldazine.

mixture of an unaminated, unhydroxylated Z-anthraquinonecarboxaldazineand ortho-dichlorobenzene at a temperature above 60 C., while passingchlorine therethrough. 10 N0 references cited.

5. The process of claim 2 in which the aldazine islnitroanthraquinone-Z-carboxaldazine.

1. A PROCESS OF PREPARING AN UNAMINATED, UNHYDROXYLATED2-CYANOANTHRAQUINONE WHICH COMPRISES HEATING A MIXTURE OF AN UNAMINATED,UNHYDROXYLATED 2-ANTHRAQUINONECARBOXALDAZINE AND ORTHO-DICHLOROBENZENEAT A TEMPERATURE ABOVE 60*C., WHILE PASSING CHLORINE THERETHROUGH.